Currently, electronic devices, such as mobile phones and tablet computers are often equipped with microphone holes. Users can transfer sound information through the microphone hole to receivers. The microphone hole is usually accommodated in an electronic device housing, and a dust-proof net is usually attached to the inside of the electronic device housing to cover the microphone hole. In attaching the dust-proof net, a part of the dust-proof net can be attached with double sided adhesive, and then the part of the dust-proof net with the double sided adhesive can be attached to the electronic housing, and the other part of the dust-proof net without the double sided adhesive can cover the microphone hole. As sizes of the microphone hole and the dust-proof net are small, the dust-proof net is difficult to accurately position and the double sided adhesive may cover the microphone hole.